Hydrogen Isotope and Water Content Analysis of Ultralow Volume Volcanic Glass.

Hydrogen isotope and H2O content of hydrated volcanic glass are useful proxies for paleoelevation and paleoclimate reconstruction. However, their analysis remains challenging because conventional bulk methods typically require relatively large amounts (∼10-3-10-2 g) of purified and fresh volcanic glass. Volcanic glass from the Mesozoic sediments and scientific drilling core samples is commonly affected by alteration and grain-scale heterogeneity, and the available sample mass is often insufficient for bulk analysis. Here, we present an ultralow sample consumption (∼10-9 g) in situ method for determining H2O contents and hydrogen isotope of hydrated volcanic glass from Early Cretaceous tuffs. This approach extends such analyses to older and less-well-preserved materials and provides a practical basis for high-resolution paleoenvironmental reconstruction.